TY - JOUR
T1 - Ordering of ferromagnetic nanoparticles in nematic liquid crystals
AU - Dierking, I.
AU - Heberle, M.
AU - Osipov, M. A.
AU - Giesselmann, F.
PY - 2017/7/14
Y1 - 2017/7/14
N2 - Dispersions of magnetic nanoparticles in a nematic liquid crystal were investigated as magnetic fields were applied in three different boundary condition geometries: (i) planar substrates and B ⊥ n, (ii) planar substrates and B / n, and (iii) homeotropic substrates and B ⊥ n. Particle chaining is observed when a magnetic field is applied, with a periodicity perpendicular to the chains. Furthermore, linear chains are observed for the magnetic field applied perpendicular to the director, while zigzag chains are formed when the magnetic field direction is parallel to the director field. This is attributed to a change from a dipolar defect configuration around dispersed nanoparticles, to a quadrupolar one, i.e. the change from satellite to Saturn-ring defects. This effect is largely independent of the sample thickness. The dynamic development of the chain length, as well as their two-dimensional order parameter was studied in all cases. Chain lengths increased rapidly until saturation at approximately l = 30 μm after a time of about t = 10 s. Similarly, the chain order parameters increased until saturation between S = 0.8-0.9, independent of sample geometry.
AB - Dispersions of magnetic nanoparticles in a nematic liquid crystal were investigated as magnetic fields were applied in three different boundary condition geometries: (i) planar substrates and B ⊥ n, (ii) planar substrates and B / n, and (iii) homeotropic substrates and B ⊥ n. Particle chaining is observed when a magnetic field is applied, with a periodicity perpendicular to the chains. Furthermore, linear chains are observed for the magnetic field applied perpendicular to the director, while zigzag chains are formed when the magnetic field direction is parallel to the director field. This is attributed to a change from a dipolar defect configuration around dispersed nanoparticles, to a quadrupolar one, i.e. the change from satellite to Saturn-ring defects. This effect is largely independent of the sample thickness. The dynamic development of the chain length, as well as their two-dimensional order parameter was studied in all cases. Chain lengths increased rapidly until saturation at approximately l = 30 μm after a time of about t = 10 s. Similarly, the chain order parameters increased until saturation between S = 0.8-0.9, independent of sample geometry.
KW - magnetic nanoparticles
KW - liquid crystal
KW - boundary condition geometries
KW - particle chaining
UR - http://www.scopus.com/inward/record.url?scp=85021832977&partnerID=8YFLogxK
UR - http://pubs.rsc.org/en/journals/journalissues/sm#!recentarticles&adv
U2 - 10.1039/C7SM01029J
DO - 10.1039/C7SM01029J
M3 - Article
AN - SCOPUS:85021832977
SN - 1744-683X
VL - 13
SP - 4636
EP - 4643
JO - Soft Matter
JF - Soft Matter
IS - 26
ER -